In stereoscopic reproduction methods for three-dimensional representations, the two perspective-shifted images must be visible separately to each eye. Depending on the stereoscopic method, reproduction techniques are used that work with color filters, polarization filters or with consecutively reproduced individual images. One of the older techniques is that using color filter glasses, also known as anaglyph glasses.
In this technique, the two images for the right and left eye are colored in two colors. The color filter in front of one eye allows only the image components of the color filter to pass, and the same applies to the color filter in front of the other eye.
Since the two images are offset in perspective, the viewer perceives two offset images that the brain interprets into a three-dimensional image with depth effect.
The process originates from early cinema technology. In the early years, complementary colorssuch as red and cyan were used as color filters. Later, these filters were replaced by red- green filters and other color combinations that produced better results.